1. Field of the Invention
The present invention relates to an imaging system, and more specifically, to an imaging system, an imaging apparatus, and a system for generating an image.
2. Description of the Related Art
In recent years, cameras have been put into practical use that can capture, with one shot, a still image in a hemispherical or full spherical field of view. Handheld-size cameras are also available that can capture an omnidirectional still image. The body of such a handheld size camera is liable to tilt, so that cameras are known that have a function of displaying a captured still image after correcting the tilt thereof in response to photographing when the camera body is tilted.
Japanese Patent Application Laid-open No. 2013-214947 is known as a technique to correct the tilt of the still image. In order to obtain a still image having the correct vertical direction, Patent Document 1 discloses a configuration of a still image capturing device having two fisheye lenses in which a parameter for converting a fisheye image into a regular image is calculated according to a tilt angle detected by an acceleration sensor provided in the still image capturing device for obtaining a tilt from the vertical direction.
In addition to cameras for still images, cameras have also been developed that can store therein a wide range as a video image using an ultra-wide-angle lens.
Among cameras for capturing a video image according to conventional techniques, cameras are known that have a function to reduce blurring associated with hand movement. However, when the video image is captured while a camera body is tilted, the vertical direction thereof differs from the zenith direction of a video image capturing device, thereby causing a problem. Specifically, when a viewer views the video image captured while the camera body is tilted, if a field of view is changed while the vertical direction is held coincident with the original direction, a complex rotation occurs, and thus may give the viewer uncomfortable feeling such as 3D sickness. The conventional technique of Patent Document 1 is a technique for dealing with still images, and is not a technique that enables creation of video images having the correct vertical direction. Due to this problem, development of a technique is desired with which an omnidirectional video having the correct vertical direction is generated regardless of the tilt state of the camera.
Therefore, there is a need for an imaging system, an imaging apparatus, and a system that enable to detect a tilt of an image capturing unit with respect to a reference direction, and generate video data that is corrected in tilt according to the detected tilt.